Field of the Invention
The present invention relates to a radiation imaging apparatus and a method of controlling a radiation imaging apparatus.
Description of the Related Art
Regarding radiation imaging apparatuses, gain correction is performed in order to suppress pixel sensitivity fluctuation, but there are cases in which if pixel nonlinearity is large, pixel sensitivity fluctuation remains even with gain correction, and a signal-to-noise ratio (SNR) of an image is reduced.
In non-patent document 1 (C. Schmidgunst et al. “Calibration model of a dual gain flat panel detector for 2D and 3D x-ray imaging”, Medical physics 34(9) page 3649 (2007)), multi-point gain correction that makes precise approximations by gain correction to improve the high dose side SNR of the image by obtaining a plurality of calibration points is disclosed. Also, in patent literature 1 (Japanese Patent Laid-Open No. 2014-13950), as an improvement of multi-point gain correction, a method in which a low-dose region of a gain correction is approximated by a linear expression, and a high-dose region is approximated by a polynomial expression is disclosed.
However, a large number of calibration points is necessary to ensure a high signal-to-noise ratio when applying the method recited in patent literature 1 and non-patent document 1.
The present invention, in view of the foregoing problem, provides a capturing technique by which it is possible to obtain a high signal-to-noise ratio image with less calibration points.